THREE EASY STEPS TO INTERPRET ABG

ABG tells the activity of two systems in the body. If one system is disturbed, the other tries to restore balance. Both systems are concerned about keeping blood pH in the normal range.

ABG measures pH, levels of oxygen and carbon dioxide from an artery.

It is used to measure the lung function.

COMPONENTS AND NORMAL RANGE :

COMPONENTS	NORMAL RANGE
pH	7.35 – 7.45
Partial pressure of oxygen(PaO2)	75 – 100 mm Hg
Partial pressure of carbon dioxide(PaCO2)	35- 45 mmHg
Bicarbonate (HCO3)	22 – 26 mEq/L
Oxygen Saturation	95 – 100%

STEPS FOR EASY INTERPRETATION OF ABG

ROME Method

·         Respiratory Opposite – pH and CO₂ goes in opposite direction

·         Metabolic Equal  – pH and CO₂ goes in same direction

STEP 1 : IDENTIFY THE PLACE OF pH

·         Normal  7.35 – 7.45

·         Acidosis  < 7.35

·         Alkalosis >7.45

STEP 2 : IDENTIFY IF PaCO₂ IS

·         Normal  35 -45

·         Acidosis  < 35

·         Alkalosis >45

STEP 3 : IDENTIFY IF HCO₃ IS

·         Normal  22- 26

·         Acidosis  < 22

·         Alkalosis >26

AIM TO IDENTIFY THROUGH ABG ?

·         Acidosis/ Alkalosis

·         Respiratory/Metabolic

·         Fully/Partially Compensated Or Uncompensated

AIM 1:  DETERMINE ACIDOSIS/ALKALOSIS WITH THE HELP OF pH

·         Normal  7.35 – 7.45

·         Acidosis  < 7.35

·         Alkalosis >7.45

pH	INTERPRETATION
INCREASED	ALKALOSIS
DECREASED	ACIDOSIS

AIM 2 : DETERMINE METABOLIC/RESPIRATORY – REMEMBER ROME METHOD

·         Respiratory Opposite – pH and CO₂ goes in opposite direction

pH	PaCO2	HCO3	INTERPRETATION
INCREASED	DECREASED	NORMAL	ALKALOSIS
DECREASED	INCREASED	NORMAL	ACIDOSIS

·         Metabolic  Equal  – pH and CO₂ goes in same direction

pH	PaCO2	HCO3	INTERPRETATION
INCREASED	NORMAL	INCREASED	ALKALOSIS
DECREASED	NORMAL	DECREASED	ACIDOSIS

AIM 3 : DETERMINE COMPENSATION

·         If pH  is normal – fully compensated

·         If all three values are abnormal – partially compensated

·         If PaCO₂ or HCO₃ is normal and the other is abnormal.

RESPIRATORY ALKALOSIS

pH	PaCO2	HCO3	INTERPRETATION
INCREASED	DECREASED	NORMAL	UNCOMPENSATED
INCREASED	DECREASED	DECREASED	PARTIALLY COMPENSATED
NORMAL	DECREASED	DECREASED	FULLY COMPENSATED

RESPIRATORY   ACIDOSIS

pH	PaCO2	HCO3	INTERPRETATION
DECREASED	INCREASED	NORMAL	UNCOMPENSATED
DECREASED	INCREASED	INCREASED	PARTIALLY COMPENSATED
NORMAL	INCREASED	INCREASED	FULLY COMPENSATED

METABOLIC ACIDOSIS

                      

pH	PaCO2	HCO3	INTERPRETATION
DECREASED	NORMAL	DECREASED	UNCOMPENSATED
DECREASED	DECREASED	DECREASED	PARTIALLY COMPENSATED
NORMAL	DECREASED	DECREASED	FULLY COMPENSATED

 METABOLIC ALKALOSIS

                       

pH	PaCO2	HCO3	INTERPRETATION
INCREASED	NORMAL	INCREASED	UNCOMPENSATED
INCREASED	INCREASED	INCREASED	PARTIALLY COMPENSATED
NORMAL	INCREASED	INCREASED	FULLY COMPENSATED